Heretofore, what is called a pointing device has been used for a cellular phone, a PDA (personal digital assistance), a notebook personal computer (hereinafter, referred to as a notebook PC), a game machine or the like. As one of input devices, the pointing device has a function to move a display position of an object to be controlled (a pointer, a cursor or the like) on a display screen in response to operating force to an arbitrary direction by a user (hereinafter, also referred to as “an operator” in some cases). As a generally-used pointing device, an analog pointing device such as a mouse, a track ball and a joystick has been widely used.
In control of such a conventional pointing device, it is common to calculate a relative operating position with respect to a certain reference point by use of a two-dimensional coordinate system or polar coordinate system of an operating direction α and an amount of operation β.
FIG. 7 is a view showing a relationship between the operating direction and the amount of operation in a conventional pointing device.
More specifically, this drawing shows a relationship between an operating direction and an amount of operation in a joystick type pointing device as an object, which designates a reference point O as a center and performs the control based on an operating direction and an amount of operation from the reference point O. In this drawing, in which the reference point in the system of coordinates is defined as (0, 0) and the operating position in the system of coordinates as A(x, y). In this case, each of x and y takes on any value of a positive value, a negative value and zero. Then, the operating direction α is determined by a ratio of the x and the y and by a combination of the x and they, each of which takes on any value of a positive value, a negative value and zero. Note that the case where both of the x and the y are zero is excluded.
Here, when the operating direction is defined as an angle of measure α in radians (−π≦α≦π), the operating direction α in the pointing device of the above-described conventional system can be uniquely determined as shown below. Specifically, equations can be represented as:(when x=0, y>0): α=π/2;(when x=0, y<0): α=−π/2;(when x>0, y=0): α=0;(other than when x>0, y=0): α=tan−1(y/x);(when x<0, y=0): α=π;(when x<0, y>0): α=π+tan−1(y/x); and(when x<0, y<0): α=−π+tan−1(y/x).Moreover, the amount of operation β in this case can be represented as:β=(x2+y2)0.5 Furthermore, arithmetic operations of trigonometric functions are included in this calculation, and therefore, a translation table is used in order to increase processing speed in some cases.
In the control of the conventional pointing device, as described above, it is common to use the relative operating position (x, y) with respect to the reference point O or parameters such as the operating direction α and the amount of operation β. Furthermore, the moving speed of the object to be operated (the pointer, the cursor or the like), which is displayed on a display 208A, is changed in response to a magnitude of the amount of operation β obtained in the procedure as described above. Here, examples of relationships between the amounts of operation β and the moving speeds V are shown in FIGS. 8A to 8G.
FIGS. 8A to 8G are explanatory views showing the relationships between the amounts of operation and operating speeds in the conventional pointing devices.
As shown in these drawings, in the conventional pointing device, there are examples such as:                Example of linearly increasing the speed V in response to the amount of operation β (FIG. 8A);        Examples in each of which a plurality of increasing gradients of the speed V are present (FIGS. 8B to 8D);        Examples of non-linear relationship between the amount of operation β and the speed V (FIGS. 8E and 8F); and        Example of the speed V constant with respect to the amount of operation β (FIG. 8G).        
With regard to these analog pointing devices, it is common to choose an object to be operated (the pointer, the cursor or the like), which is small on the display screen, as a utilization mode thereof. Specifically, in the utilization mode of the conventional pointing device, a delicate operation such as drawing a picture or a character is required for the pointing device in many cases, and accordingly, resolution thereof in the moving direction is relatively high in many cases. However, that the high resolution causes a slight directional shift to appear in the moving direction as it is. For this reason, in the case of moving the object to be controlled, such as the pointer, to an expected position on the display, the user of such a pointing device tends to slightly shift or stagger the object to be controlled (or the operating position). Hence, it is very frequent that the operator cannot be satisfied with an operation feeling of the conventional pointing device.
Moreover, the tendency of the operating position towards being shifted due to the above-described resolution is particularly evident in a portable electronic instrument such as the cellular phone and the compact PDA, for which the pointing device itself is required to be miniaturized.
Specifically, in the portable electronic instrument (a portable communications terminal device such as the cellular phone, and an information processing apparatus such as the PDA), in general, a casing thereof is compact. Accordingly, on such a portable electronic instrument, a device made in consideration of a size and motion of a hand of the user, that is what-is-called a full-scaled keyboard is difficult to mount. Therefore, in the portable electronic instrument, the pointing device plays an important role as a man-machine interface between the user and the electronic instrument. However, under such circumstances, in the actual portable electronic instrument, it is difficult to ensure a sufficient area for mounting the pointing device due to limitations of a size of the casing.
Hence, the portable electronic instrument under such circumstances has a problem that the portable electronic-instrument cannot give a sufficiently comfortable operation feeling to the user.
In this connection, for example, in Japanese Patent Laid-Open No. H5 (1993)-265649 (hereinafter, referred to as Patent Document 1), a pointing device which adjusts such a shift is disclosed.
In this Patent Document 1, first, an ARCTAN value of the pointing device is calculated by means of outputs of two sensors. Then, in Patent Document 1, actual outputs of the sensors are adjusted to approximate values thereto so that the ARCTAN value can be 0, 45, 90, 135, 180, 225 and 270. In such a way, in Patent Document 1, a configuration is formed in which data can be obtained as a displacement in a specific direction even if the pointing device is roughly operated.
According to such an adjustment method, it is possible to realize the adjustment by a relatively simple control system. However, the operator who operates the pointing device has a habit inherent in him/herself. For this reason, only in accordance with such an adjustment method, there is no other way but the operator conforms his/her operation with this adjustment method, causing a problem of low adaptability in some cases.
Accordingly, for example, in Japanese Patent Laid-Open No. H10 (1998)-154038 (hereinafter, referred to as Patent Document 2), disclosed is a pointing input device which stores a shift from a reference direction as personal data and adjusts a shift caused the habit inherent in the operator.
However, in the case of such adjustment control which stores the personal data and performs the adjustment as in Patent Document 2, the control system sometimes becomes complicated.